Final answer:
The cosmic microwave background radiation has slight temperature fluctuations indicative of structural seeds in the early universe. Causes include quantum fluctuations and gravitational effects of matter, with variations aligning with predictions of inflationary models.
Step-by-step explanation:
The cosmic microwave background radiation (CMBR) is not entirely uniform in space. It exhibits slight fluctuations in temperature, indicative of hot and cold regions. These variations are significant because they represent the earliest seeds of structure in the universe. Two principal causes of these wrinkles in the CMBR are quantum fluctuations during the inflationary period of the early universe and the gravitational effect of matter as the universe evolved.
The temperature of the CMBR is extremely uniform overall, with a remarkably perfect blackbody radiation spectrum corresponding to a temperature of 2.725 ± 0.002 K. However, the anisotropies or temperature variations in the CMBR are at the microkelvin level, which were both less than some predictions but precisely within the range that models of inflation and cosmic structure formation would suggest. The detection and measurement of these variations have helped scientists to understand the universe's infancy and confirm the theory of the Big Bang.